As illustrated in FIG. 12 as an example, a unit panel 3 is typically mounted on the upper surface of an arm rest 2 of a door trim 1, and the unit panel 3 contains therein operating knobs 4 for operating power window switches which open and close corresponding window glass sheets, and an operating knob 5 for a door lock switch.
To operate a power window or activate a door lock at night, one has to grope for such knobs because the passenger compartment is dark at such a time. Therefore, it has been proposed to provide an illuminating system in which an opening 6 is provided in each of the operating knobs 4 and 5 so that the area surrounding the operating knobs 4 and 5 may be illuminated by the light from an internally positioning lamp 7 passed through the opening 6.
However, with only the light from the positioning lamp 7, it is difficult to distinguish the operating knobs from one another, and it has been desired to improve the convenience in the operation of power window switches and door lock switches.
Further, the unit panel 3 is typically provided with an ash tray, and it has been pointed out that an occupant may spill cigarette ash when he tries to reach for the ash tray in the dark, and litter the passenger compartment.